Apparatus for interlacing filaments of multifilament yarns

ABSTRACT

Multifilament yarn is interlaced by passing the yarn through an apparatus which impinges four streams or jets of fluid upon the yarn. The jets or streams of fluid are given a rotational component by auxiliary streams of air which impinge on the jets or streams with a tangential attitude. The yarn and impinging streams of fluid converge in a cavity located within an interlacing chamber wherein the height of the cavity is no greater than the smallest diameter of the cavity and wherein the inlet of the interlacing chamber is wider than the diameter of the cavity and the outlet of the interlacing chamber is narrower than the cavity.

United States Patent [191 Blanc et al.

APPARATUS FOR INTERLACING FILAMENTS OF MULTIFILAMENT YARNS lnventors:Charles Blanc. Couzon au Mont dOr; Christian Delarue, Meyzieu, both ofFrance Rhone-Poulenc-Textile, Paris, France Filed: Feb. 1, 1974 Appl.No.: 438,684

Assignee:

Foreign Application Priority Data Mar. 5. 1973 France 73.08029References Cited UNITED STATES PATENTS Bauer 28/14 1 Apr. 8, 19753,167,847 2/1965 Gonsalves 28/].4 3,364,537 1/1968 Bunting et a1. 28/l.43,525,133 8/1970 28/1.4

3.673.648 7/1972. Thacker 28/1.4

Primary E.\'anrinerL0uiS K. Rimrodt Attorney. Agent, or F irmSherman &Shalloway [57] ABSTRACT Multifilament yarn is interlaced by passing theyarn through an apparatus which impinges four streams or jets of fluidupon the yarn. The jets or streams of fluid are given a rotationalcomponent by auxiliary streams of air which impinge on the jets orstreams with a tangential attitude. The yarn and impinging streams offluid converge in a cavity located within an interlacing chamber whereinthe height of the cavity is no greater than the smallest diameter of thecavity and wherein the inlet of the interlacing chamber is wider thanthe diameter of the cavity and the outlet of the interlacing chamber isnarrower than the cavity.

18 Claims, 7 Drawing Figures AND APPARATUS FOR INTERLACING FILAMENTS OFMULTIFILAMENT YARNS BACKGROUND OF THE INVENTION 1. Field of theInvention The instant invention relates to methods of and apparatus forthe manufacture of multifilament yarns having interlaced filaments. Moreparticularly, the instant invention relates to methods and apparatus forthe manufacture of multifilament yarns having interlaced filamentswherein the filaments are interlaced by impinging at least one stream offluid on the yarn.

2. Technical Considerations and Prior Art The filaments of multifilamentyarns are cohered together by processes such as twisting, sizing orinterlacing. The present invention is directed to interlacing wherein ayarn formed of continuous multifilaments is interlaced or tangled in agenerally random way to form pseudo burls which cooperate to form a yarnthat has a total twist which may be substantially zero.

The prior art suggests several processes for the man ufacture ofinterlaced yarn. These processes include subjecting the yarn, whileunder slight tension, to the action of at least one fluid jet which isgenerally created by compressed air. Generally the jet is directed in aplane that is substantially normal to the direction in which the yarnadvances and is impinged on the yarn as the yarn traverses what isgenerally known as an interlacing nozzle" or interlace nozzle."

The patent literature. especially the French patent literature. containsmany examples of interlacing methods and apparatus for utilization ininterlacing the fibers of multifiber yarn. In addition No. 68,429 toFrench Pat. No. 1,108,890 a strand of multifiber yarn is advancedbetween a delivery tube which impinges fluid against the strand and aresonance box. An improvement to this invention is disclosed in FrenchPat. No. 1,334,130 in which the impinging fluid is recycled from theoutlet of the resonance box and again impinged on the yarn.

French Pat. No. 1,492,945 discloses a process in which a multifilamentstrand of yarn is subjected simultaneously to impingement from pairs ofprimary fluid jets and at least one secondary jet which impinges fluidon the yarn from a direction opposite that of the primary jets in a zonebetween the points of impact of the primary jets.

French Pat. No. 2,094,232 discloses a process in which yarn is passedthrough a conduit and subjected to impingement from two fluid jets whichare substantially aligned with the conduit but are oppositely directed.

The aforedescribed processes impinge substantially rectilinear fluidjets on multifilament yarns to interlace the filaments of the yarns.However, there is another approach in which the multifilament yarn isadvanced through a zone or station in which there is vortex turbulencecreated by impinging fluid jets on the yarn which have an axis ofrotation which is substantially parallel to the direction in which theyarn advances. In the processes disclosed in these patents, the fluid isfed directly into a conduit forming the interlacing zone or station andthe vortex turbulence is formed in the conduit itself. Consequently, inorder for the vortex turbulence to be effective, the conduit must extenda relatively long distance and a plurality of inlets for the fluid jetsneed to be distributed in the conduit along the path therethroughassumed by the yarn.

U.S. Pat. No. 2,191,791 discloses a yarn guide composed of a cavity, theheight of which is at most equal to the diameter thereof. As the yarnpasses through the cavity, a plurality of radial jets impinge fluidstreams upon the yarn and as a result of the action of radial streams,the yarn is interlaced.

Frence Pat. application No. 72/19404, filed May 25, 1972 now French Pat.No. 2,186,029, in the name of the inventor of the instant invention andentitled Process and Device for the Manufacture of Interlaced StrandYarn is subjected to impingement from jets which generate a perturbedfluid flow. By the term per turbed fluid flow is meant a stream of fluidhaving a direction and possibly an output which is temporarily variable.With the process disclosed in this application, the interlacing qualityof the multifilament yarn is very good because over short lengths thereis a random pattern of interlacing without a geometric repetitionwhereas, over long lengths, the yarn has a pleasing regular appearance.Unfortunately, the apparatus for practicing the process disclosed inthis application is rather complicated because it relies on movablemechanical elements to cause perturbation of the fluid jets.Furthermore, this process is relatively noisy and the mechanicalelements involved are subject to rapid wear. Finally, it is difficult toobtain similarities in interlacing configurations produced by differentnozzles.

SUMMARY OF THE INVENTION In view of the aforementioned difficultiesencountered upon using the methods and apparatus of the prior art, it isan object of the instant invention to provide new and improved methodsof and apparatus for interlacing the filaments of multifilament yarn.

It is another object of the instant invention to provide new andimproved methods of and apparatus for interlacing the filaments ofmultifilament yarn by utilizing a relatively simple apparatus which hasno parts that move while the interlacing'process is being effected.

It is another object of the instant invention to provide new andimproved methods of and apparatus for interlacing filaments ofmultifilament yarns wherein the interlaced filaments have improvedcohesion.

It is still another object of the instant invention to provide new andimproved methods of and apparatus for interlacing filaments ofmultifilament yarn wherein it is possible to obtain various interlacingconfigurations with the same apparatus.

It is a further object of the instant invention to provide new andimproved methods of and apparatus for interlacing filaments ofmultifilament yarn wherein interlacing occurs upon impinging a fluid jeton the yarn wherein the fluid jet has a rotating component.

In keeping with these objects and additional objects, the presentinvention contemplates an apparatus for interlacing the filaments of amultifilament yarn under the influence of an expanding pressurized fluidby advancing the yarn through an interlacing chamber havmost equal toits diameter. The present invention also contemplates methods utilizingthe features of the aforedescribed apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a nozzleaccording to the instant invention taken in section to show aninterlacing chamber and fluid conduits;

FIG. 2 is a top view of the nozzle in FIG. 1 taken in section along line2-2 of FIG. 1 showing four conduits registering with the interlacingchamber;

FIG. 3 is a half view taken in section along line 3-3 of the nozzleshown in FIG. 2 illustrating how a fluid supply line is registered withthe nozzle;

FIG. 4 is a side view in section showing a plate which is utilized forpartial closure of the outlet end of the interlacing chamber shown inthe previous figures;

FIG. 5 is a top view of the plate shown in FIG. 4;

FIG. 6 is another embodiment of a plate which is used for partialclosure of the outlet of the interlacing chamber; and

FIG. 7 is a top view of an embodiment of the nozzle according to theinvention which can be pivoted to an open position to receivemultifilament yarn therethrough in a convenient manner.

DETAILED DESCRIPTION Referring now to FIG. 1, there is shown a nozzle,designated generally by the numeral 10, which is the apparatus forperforming the process of the instant invention. The nozzle 10 has aninterlacing chamber, designated generally by the numeral 11, throughwhich passes a multifilament strand of yarn l2 and in which thefilaments of the yarn 12 are interlaced to form a unified strand ofyarn. As seen in FIG. 2, the interlacing chamber is a generallycylindrical bore formed in a block 13.

In the illustrated embodiment, the interlacing chamber 11 maintains itscylindrical configuration for a certain distance and then tapers with aconical portion 14 to form what is herein described as a treatment zone16. Downstream of the treatment zone 16, the interlacing chamber 11expands through another beveled portion 17 and continues to an outlet18. In the embodiment shown in FIG. 1, a plate 19 is bolted by screws 21(see FIG. 3) to the block 13. The plate 19 has a projecting portion 22which extends therefrom to form a converging outlet 24 therein, thepurpose of which will be explained hereinafter.

The treatment chamber 16 has an axial length which is substantiallyequal to its diameter. However, the axial length of the treatmentchamber may, if desired, be less than the diameter. Registered with thetreatment chamber 16 are pairs of opposed jets 26 and 27 extending Ialong one axis, and 28 and 29 extending along another axis, positionednormal to the first axis. In the illustrated embodiment, the axes of thejets are all included in the same plane, which plane is perpendicular tothe longitudinal direction of advance assumed by the yarn 12. Throughthese jets 26, 27, 28 and 29, fluid is passed to impinge on the yarn 12.All fluid flowing through these jets flows into the treatment zone 16.

The jets 26, 27, 28 and 29 have vortex chambers 31, 32, 33 and 34respectively associated therewith. These vortex chambers are axiallyaligned with the jets. In order to generate vertices within the vortexchambers 31, 32, 33 and 34, each vortex chamber has a tangential jet 36registered therewith in a direction which is tangent to the axes of thevortex chambers and the jets 26, 27, 28 and 29.

Connected to each vortex chamber is a principal fluid supply conduit 41which supplies the fluid stream that expands through the jets 26, 27, 28and 29, to impinge upon the yarn 12. As the principal fluid is suppliedthrough the conduits 41, the tangential jets 36 supply an auxiliaryfluid in a direction which is tangential to the flow of the principalfluid. This causes the principal fluid to rotate and form vertices whichgenerally rotate about the axes of the jets 26-29 and the vortexchambers 31-34. The auxiliary fluid is applied via conduits 42 (seeFIGS. 1 and 3) that register with bores 43 and 44 in the block 13. Thebore 43 communicates with vortex chambers 31 and 33 through tangentialjets 36 while the bore 44, which is diagonally spaced from the bore 43,communicates with vortex chambers 32 and 34 through tangential jets 36.By configuring the bores 43 and 44 in this way, it is possible to rotatethe vortices in vortex chamber 31 in the opposite direction from thevortices generated in the vortex chamber 32. Furthermore, the vorticesin vortex chamber 33 are rotated in the opposite direction from thevortices in the vortex chamber 34. This, of course, occurs because thetangential jets communicating with opposed vortex chambers 31, 32 and33, 34 are directed in opposite directions.

The block 13 has threaded holes 47 machined therein through which may beintroduced valves 51 that may be registered with the jets 36 toconstrict the inlet ends of the jets to throttle the amount of fluidentering the jets and thereby control the the intensity of vorticesgenerated in the vortex chambers 31-34. By utilizing the valves 51, thevortices in selected ones of the chambers 31-34 may be variedselectively so that fluid impinging on the yarn 12 through the jets26-29 may have varying rotation components. This produces differentvariations in interlacing configurations given to the multifilament yarn12. If desired, of course, selected ones of the jets 36 may be cut offcompletely by the valves 51 so that the principal fluid stream appliedthrough the associated vortex chamber will have no rotational component.

In addition to utilizing the bores 47 for varying rotational componentsof the principal fluid, the bores 47 may also be used upon removal ofthe valves 51 to inject auxiliary fluids, such as dyes or otherprocessing fluids, into the principal'fluid. Furthermore, the bores 47are, or may be, created as a convenient access for boring the jets 36through the block 13.

Referring now to FIGS. 4, 5 and 6, there are shown two types of plateswhich are used to partially constrict the outlet 18 of the interlacingchamber 11. The embodiment shown in FIG. 4 has already been describedand utilizes a converging portion 24 which is conical to graduallyconstrict the outlet from the interlacing chamber 11. The embodiment ofFIG. 6 shows a different configuration of the plate 19 wherein theoutlet 18 of the interlacing chamber 11 may be constricted by an abruptorifice 52.

Although no constricting means is shown as being applied to the intakeor upstream end of the interlacing chamber 11, such a device may beutilized if desired.

Referring now to FIG. 7, there is shown an embodiment of the nozzle 10wherein the block 13 is divided into a pair of symmetrical portions 13aand 13b so that the block may be conveniently opened for insertion of amultifilament yarn 12. By utilizing the configuration shown in FIG. 7,the yarn does not have to be first severed and threaded through thenozzle in order to apply the nozzle 10 to the yarn. In the embodimentillustrated in FIG. 7, the two halves 13a and 13b are pivoted by pins 63and 64 to a plate 70 so as to swing toward and away from one another.The portion 13a has a handle 65 rigidly secured thereto and a pin 66projecting therefrom. When the halves 13a and 13b are pivoted intoabutting relationship along the interface 67, the pin 66 is engaged by alatch 68. The latch 68 has a curved slot 69 therein which engages thepin 66 and captures as a handle 71 is rotated in the counterclockwisedirection. In order to, in effect. cam the two halves 13a and 13);together, the handle 71 is pivoted offcenter about a pin 72 so as thehandle is rotated the pin 66 is drawn progressively closer to the pin72. By utilizing the arrangement of the off-center latch 68 and plate70, an articulated locking system is provided in which absorption ofplay between the two halves 13a and 13!) may be accomplished byauxiliary structures, such as spring washers, positioned to act betweenthe two halves 13a and 13b.

While in the illustrated embodiment the fluid utilized is air. it shouldbe kept in mind that any other gas or liquid or a diphase liquid. suchas an emulsion, may be used. In addition, it should be kept in mind thatthe fluid utilized may contain a dye.

Furthermore, although the interlacing chamber 11 and treatment zone 16disclosed in the drawings are generally cylindrical in configuration. itshould be kept in mind that these portions of the nozzle 10 may have asurface defined by any convenient surface of revolution so that thediameter may vary from one end to the other.

Although the jets 26, 27, 28 and 29 are shown having axes all in thesame plane, these jets may be inclined relative to that plane so as togenerate a traction on the yarn 12 as the fluid passes through the jetsand impinges on the yarn.

While four jets 26, 27, 28 and 29 are illustrated as being positioned atan angle of 90 to one another, it is possible to utilize any numberofjets the angle between which may vary between 0 and 80 and preferablymay vary between 30 and 80.

In the illustrated embodiment, the fluid ejected from adjacent jets mayrotate in the same direction or in opposite directions. If the fluidfrom adjacent jets rotates in opposite directions, it is possible toavoid parasitic false twist effects on the multifilament yarn as it isinterlaced.

Although the jets 26-29 and the vortex chambers 31-34 are shown ashaving cylindrical side walls, it is also possible to profile thesestructures to have the form of a Laval nozzle which is convergent anddivergent. Such a configuration would enhance the speed of ejection offluids through these structures while at the same time reducingconsumption of fluid to produce the same interlacing effect on the yarn.

Finally, the configuration of the yarn 12, as it emerges from theinterlacing chamber 1 1, may be varied according to whether or not theoutlet 18 of the chamber is constricted. If the outlet of the chamber isconstricted by, for example, the converging surface 24 shown in FIGS. 1,3 and'4, or the converging surface 52 shown in FIG. 5, an improvement inyarn cohesion results because the exit speed of the fluid is increased.If the opening 18 is wider than the diameter of the treatment zone, thenthe yarn, as it exists from the interlacing chamber, will swell creatingan effect which might, under some circumstances, be desired.

EXAMPLES By using the nozzle 10 shown in FIGS. l-6, the followingresults were obtained.

EXAMPLE I Texturized polyamide yarn having a count of 2800 dtx/136strand was processed using the nozzel l0 and the plate 19 with thegradually converging outlet defined by surface 24. Compressed air wasapplied to the conduits 41 and 42 with the same pressure. For a givenpassage of the yarn through the nozzle 10, the quality of theinterlacing of the yarn was measured as a function of this pressure. Theoperation as repeated for different speeds and the pressure read on amanometer and expressed in bars.

The cohesion factor of the interlacing was measured on an entanglementtester R-2040," Rothschild (Zurich). This entanglement tester works onthe principal of automatic detection of the distance between points ofinterlacing by utilizing a needle that penetrates between the filamentsof a moving yarn and retracts as soon as it encounters a point ofresistance, the point of resistance being an interlace point. The yarnbeing tested is first subjected to a known adjustable pretensioning.Since the threshold of tension that corresponds to disengagement of theneedle from the yarn is known and adjustable, the cohesion factor can beexpressed by the relationship: F= /11 wherein d is the average dis- Stance between interlace points expressed in centimeters and is theaverage of at least 100 measurements. The values of the interlace factorare presented in the following table in which PI is the injectionpressure of the principal fluid, P.T. is the injection pressure of theauxiliary fluid used to create the turbulence and V is the yarn speed inmeters per minute.

Table I O 5 l l 5 2 3 4 5 6 P. V. fil

200 l0.6 24.3 27.l 38.6 47.4 48.8 65.5 58.5 300 9.68 20.1 25.4 35.5 45.556.9 50.7 55.6 400 ll.9 16.8 26 2 26.6 43 49.4 52.2 53.7 1070 7.2 18.529.5 35.1 40.l

EXAMPLE 2 The operating conditions in this example are the same as inExample 1 except that the nozzle functioned without feeding turbulencefluid. In this example, no

fluid pressure was applied to conduits 42 while the conduits 41 werepressurized.

A review of Table 11 results in the following observations:

1. For a given speed of yarn passage. the interlace factor is directlyproportional to the injection pressure; and

2. At rather a narrow speed range, the speed has little effect on thevalue of the interlace factor.

COMPARISON OF EXAMPLES 1 AND 2 In comparing Examples 1 and 2, it isobserved that the interlacing factor is in direct proportion to the flowof fluid in the nozzle. It is seen that the degree of interlace of theyarn obtained with the nozzle functioning with turbulent fluid and thatof the nozzle functioning without turbulent fluid are substantiallyequivalent. However, in the case of the nozzle functioning withturbulent fluid, it is found that the flow of air passing through thenozzle is substantially reduced on the order of percent. Consequently,there is a considerable saving in fluid. Furthermore, the interlaceproduced is more regular, as evidenced by the separation of measurementson the Rothschild apparatus which deviates from the average less. Theresulting yarn appears more regular. more sheathed and with very slightvariations in diameter when turbulence is utilized.

EXAMPLE 3 In this example, the pressure of the primary fluid was keptconstant while the pressure of the turbulencecausing fluid was varied.In this example, there were three series of tests:

First series The primary injection fluid pressure was held constant at 1bar while three tests corresponding to yarn speeds of 200, 300 and 400meters per minute were run. The pressure of the turbulence-causing fluidwas varied and the results are recorded in Table 111.

Second series The same tests were made as with the first series;however, the primary injection fluid pressure was maintained at 1.5bars. The results of this series are illustrated in Table IV.

Third series The same tests were conducted as with the first and secondseries; however, the primary injection fluid pressure was maintained at2 bars. The results of these tests are in Table V.

Table IV Table V 0 1.5 2 3 4 6 V. fil

In interpreting Tables III, IV and V, it is seen that the interlacefactor varies as a function of the turbulence-causing fluid pressure.There is a minimum interlace factor which, for a given pressure ofinjection fluid, is the same at the same turbulence causing fluidpressure. Thus, for a fixed value of the injection pressure, it ispossible to modulate the value of the interlace factor by varying thepressure of the turbulence-causing fluid. By optimizing the pressure ofthe primary injection fluid and the pressure of the turbulence-causingfluid, it is possible to achieve the best nozzle efficiencies byutilizing minimum flow through the nozzle. Consequently. it is possibleto enhance cohesion of the interlaced filaments by using a speedresumption device such as the plate 19 at the outlet 18 of theinterlacing chamber.

In addition to the aforementioned advantage, the regularity of theinterlace may be improved by utilizing the nozzle according to thisinvention since the nozzle can function using various arrangements suchas activating two of the turbulence-causing jets with two nonturbulencecausing jets or any symmetrical or asymmetrical mix of activatedturbulence-causing jets. Consequently, it is possible to obtain yarnshaving different configurations of interlace by using a single nozzle10. It is also possible, with the nozzle 10 of the present invention, toproduce effects such as false twist, etc. Finally, the nozzle utilizedin the instant invention may interlace many types of multifabric yarnssuch as continuous yarns, spun products of fibers, yarns which areeither flat or textured, yarns which are natural or yarns which are madeof artificial or synthetic materials.

The aforedisclosed embodiments and examples are merely illustrative ofthe features of the instant invention, which is to be limited by onlythe following appended claims.

What is claimed is:

1. An apparatus for interlacing a multifilament strand of yarn under theinfluence of an expanding fluid comprising:

an interlacing chamber through which the yarn passes as the yarn isinterlaced wherein the chamber includes a treatment zone defined by asurface of revolution about an axis, the cavity having a diameter and aheight wherein the height is at most equal to the diameter;

at least one conduit registered with said treatment zone for injectingthe fluid into said treatment zone wherein said conduit has an axisintersecting the axis of said treatment zone; and

means aligned with said conduit for introducing a rotational componentof motion to the fluid injected through said conduit having an axisnormal to the axis of the treatment zone to cause the filaments of themultifilament yarn to interlace.

2. The apparatus of claim 1 wherein the diameter is the smallestdiameter of the treatment zone measurable on the surface of revolutionthereof.

3. The apparatus of claim 1 wherein a plurality of the conduits registerwith the treatment zone for injecting the fluid and wherein the axis ofeach conduit forms the same angle with the axis of the treatment zoneand intersects the treatment zone surface in a single plane which isnormal to the axis ofthe treatment zone so that the fluid enters thetreatment zone from each conduit at the same level and angle.

4. The apparatus of claim 3 wherein the axis of each conduit extends inthe same plane which plane is normal to the axis of the treatment zone.

5. The apparatus of claim 3 wherein the angle between the axes of twoadjacent conduits is between 30 and 180.-

6. The apparatus of claim 4 wherein the angle between the axes of twoadjacent conduits is between 30 and 180.

7. The apparatus of claim 1 wherein the means for introducing arotational component, of motion to the fluid includes a turbulencechamber coaxial with the conduit in which there is an axial intake for aprincipal stream of fluid and a generally tangential intake for anauxiliary stream of fluid which introduces the rotational component tothe principal stream.

8. The apparatus of claim 3 wherein the conduits are distributed inequal spacing about the treatment zone with the axes thereof containedin the same plane which plane extends normal to the axis of thetreatment zone.

9. The apparatus of claim 8 wherein the conduits are four in number andthe axes of the conduits are spaced apart.

10. The apparatus of claim 1 wherein the interlacing chamber downstreamof the cavity has an outlet with a diameter greater than the diameter ofthe cavity.

11. The apparatus of claim 10 wherein the fluid injected into the cavityexpands freely out of the outletv 12. The apparatus of claim 10 whereinthe outlet is constricted.

13. The apparatus of claim 12 wherein the constriction occurs abruptly.

14. The apparatus of claim 12 wherein the constriction occurs gradually.

15. The device of claim 10 wherein the interlacing chamber upstream ofthe cavity has an inlet with a diameter that is greater than thediameter of the cavity.

16. The apparatus of claim 15 further including means for inserting theyarn aligned with the inlet.

17. The apparatus of claim 1 wherein the apparatus is made of twoseparate parts which are joined along an area which intersects theinterlacing chamber so that the yarn may be placed in the interlacingchamber upon separating the two parts and may be surrounded by theinterlacing chamber upon joining the two parts.

18. The apparatus of claim 3 wherein at least one of said conduitsincludes means for injecting fluid having nonturbulent flow into thecavity at the same level as the conduits injecting fluid having a rotarycomponent. 1: 1: 1:

1. An apparatus for interlacing a multifilament strand of yarn under the influence of an expanding fluid comprising: an interlacing chamber through which the yarn passes as the yarn is interlaced wherein the chamber includes a treatment zone defined by a surface of revolution about an axis, the cavity having a diameter and a height wherein the height is at most equal to the diameter; at least one conduit registered with said treatment zone for injecting the fluid into said treatment zone wherein said conduit has an axis intersecting the axis of said treatment zone; and means aligned with said conduit for introducing a rotational component of motion to the fluid injected through said conduit having an axis normal to the axis of the treatment zone to cause the filaments of the multifilament yarn to interlace.
 2. The apparatus of claim 1 wherein the diameter is the smallest diameter of the treatment zone measurable on the surface of revolution thereof.
 3. The apparatus of claim 1 wherein a plurality of the conduits register with the treatment zone for injecting the fluid and wherein the axis of each conduit forms the same angle with the axis of the treatment zone and intersects the treatment zone surface in a single plane which is normal to the axis of the treatment zone so that the fluid enters the treatment zone from each conduit at the same level and angle.
 4. The apparatus of claim 3 wherein the axis of each conduit extends in the same plane which plane is normal to the axis of the treatment zone.
 5. The apparatus of claim 3 wherein the angle between the axes of two adjacent conduits is between 30.degree. and 180.degree..
 6. The apparatus of claim 4 wherein the angle between the axes of two adjacent conduits is between 30.degree. and 180.degree..
 7. The apparatus of claim 1 wherein the means for introducing a rotational component of motion to the fluid includes a turbulence chamber coaxial with the conduit in which there is an axial intake for a principal stream of fluid and a generally tangential intake for an auxiliary stream of fluid which introduces the rotational component to the principal stream.
 8. The apparatus of claim 3 wherein the conduits are distributed in equal spacing about the treatment zone with the axes thereof contained in the same plane which plane extends normal to the axis of the treatment zone.
 9. The apparatus of claim 8 wherein the conduits are four in number and the axes of the conduits are spaced 90.degree. apart.
 10. The apparatus of claim 1 wherein the interlacing chamber downstream of the cavity has an outlet with a diameter greater than the diameter of the cavity.
 11. The apparatus of claim 10 wherein the fluid injected into the cavity expands freely out of the outlet.
 12. The apparatus of claim 10 wherein the outlet is constricted.
 13. The apparatus of claim 12 wherein the constriction occurs abruptly.
 14. The apparatus of claim 12 wherein the constriction occurs gradually.
 15. The device of claim 10 wherein the interlacing chamber upstream of the cavity has an inlet with a diameter that is greater than the diameter of the cavity.
 16. The apparatus of claim 15 further including means for inserting the yarn aligned with the inlet.
 17. The apparatus of claim 1 wherein the apparatus is made of two separate parts which are joined along an area which intersects the interlacing chamber so that the yarn may be placed in the interlacing chamber upon separating the two parts and may be surrounded by the interlacing chamber upon joining the two parts.
 18. The apparatus of claim 3 wherein at least one of said conduits includes means for injecting fluid having nonturbulent flow into the cavity at the same level as the conduits injecting fluid having a rotary component. 